1. Technical Field of the Invention
This invention relates to a method for the manufacture of methyl tertiary butyl ether by the sequential reaction of tertiary butyl alcohol and isobutylene with methanol and to the removal of methanol from the methyl tertiary butyl ether. More particularly, this invention relates to a method for the manufacture of methyl tertiary butyl ether by the sequential reaction of tertiary butyl alcohol and isobutylene with methanol and to the removal of methanol from the methyl tertiary butyl ether formed by the reactions.
2. Prior Art
Kruse et al. U.S. Pat. No. 5,243,091 discloses a process for the manufacture of methyl tertiary butyl ether from tertiary butyl alcohol and methanol wherein tertiary butyl alcohol is reacted with methanol in a primary reaction zone to provide a reaction product comprising methyl tertiary butyl ether, unreacted tertiary butyl alcohol, unreacted methanol, isobutylene and water, wherein the reaction product is separated in a distillation zone into a lighter fraction comprising methanol, isobutylene and methyl tertiary butyl ether and a heavier fraction comprising tertiary butyl alcohol, methanol and water, and wherein the lighter fraction is charged to a finishing reactor wherein isobutylene and methanol are reacted to form additional methyl tertiary butyl ether.
In copending coassigned application Ser. No. 08/147,508, filed Nov. 5, 1993 now U.S. Pat. No. 5,395,982 and entitled "Continuous Isobutylene Assisted Aqueous Extraction of Methanol from Methyl Tertiary Butyl Ether" there is disclosed a method for the continuous purification of methyl tertiary butyl ether contaminated with isobutylene, methanol and water, by the sequential steps of water extraction in the presence of an added isobutylene stripping agent to form an extract and a raffinate, distillation of the raffinate to form a heavier product methyl tertiary butyl ether fraction and a lighter isobutylene fraction from which isobutylene is recovered for recycle to the extraction zone.
In the process of Kruse et al. U.S. Pat. No. 5,243,091, tertiary butyl alcohol is reacted with methanol to provide a primary reaction product that is distilled to provide a methyl tertiary butyl ether distillation fraction that is contaminated with methanol and isobutylene. The methyl tertiary butyl ether distillation fraction is reacted with methanol to provide additional methyl tertiary butyl ether, and the methanol-contaminated isobutylene reaction product is washed with water to remove the methanol and to forman aqueous raffinate, which contains both methyl tertiary butyl ether and isobutylene that is distilled in a drying distillation column to separate the methyl tertiary butyl ether from the isobutylene and water.
In copending coassigned Preston et al. U.S. patent application Ser. No. 08/345,663, filed Nov. 28, 1994, and entitled "Sequential Reaction of TBA with Isobutylene and Methanol" (D#82,040), a process is disclosed wherein tertiary butyl alcohol and methanol are reacted, as in Kruse et al. to form a primary reaction product. Preston et al. water wash the methyl tertiary butyl ether distillation fraction, distill the raffinate from the water washing step to separate the methyl tertiary butyl ether from isobutylene and water and to forman isobutylene fraction that is reacted with methanol in a secondary reaction zone to form a secondary etherification reaction product comprising water, methanol, isobutylene, dimethyl ether, tertiary butyl alcohol and methyl tertiary butyl ether.
Gupta U.S. Pat. No. 5,292,964 also discloses a process for the manufacture of methyl tertiary butyl ether from tertiary butyl alcohol and methanol wherein tertiary butyl alcohol is reacted with methanol in a primary reaction zone to provide a reaction product comprising methyl tertiary butyl ether, unreacted tertiary butyl alcohol, unreacted methanol and water, wherein the reaction product is separated in a distillation zone into a lighter fraction comprising substantially anhydrous methanol and methyl tertiary butyl ether and a heavier fraction comprising tertiary butyl alcohol, methanol and water, and wherein the lighter fraction is charged to a finishing reactor wherein the methanol is reacted with isobutylene to form additional methyl tertiary butyl ether.
In U.S. Pat. No. 4,144,138 (1979) to Rao et al., there is disclosed a method for recovering methyl tertiary butyl ether from an etherification reaction effluent by azeotropic distillation to recover a methanol-ether azeotrope overhead which is water-washed to give pure ether raffinate, the latter being azeotropically distilled to yield an ether-methanol overhead which is recycled to water washing.
The preparation of methyl tert-butyl ether from methyl and tert-butyl alcohols is discussed in S. V. Rozhkov et al., Prevrashch Uglevodorodov, Kislotno-Osnovn. Geterogennykh Katal. Tezisy Dokl., Vses. Konf., 1977, 150 (C. A. 92:58165y). Here the TBA and methanol undergo etherification over KU-2 strongly acidic sulfopolystyrene cation-exchangers under mild conditions. This reference contains data on basic parameters of such a process.